car idles at around 1300 rpms, and sometimes between lights just slowing down, it idles around 1800 for around 6-7 seconds, and then it will slowly decline back down to 1300...
throttle position sensor? maybe just needs to be tuned still? whats goin on in there...
i had the same prob. but whenever i put the clutch in it would kick up to like 2200 and sloooowly drop down and it happened every time the clutch was in.
i tried 2 IAC's (GP sorenson and Ford brand) and neither fixed it.
ended up being a vacuum leak where the return plenum meets the intake manny.
so for u i'd say try an IAC and if not, start lookin for leaks.
I had the same problem earlier this year. It was a combination of intake plenum leaks AND fuel injector seals. After both were fixed it runs perfectly now.